The story of poker in America begins in the south and west, but by April 12, 1861 — the day Confederate forces fired on a Union garrison at Fort Sumter in South Carolina to launch the first battle of the Civil War — the game had already found its way both north and east via steamboats, trains, and by other means.
The war itself would hasten the spread of the game even more, both during the four years of fighting and afterwards. Many thousands of young men on both sides would be first introduced to poker (and other gambling games) during those years.